The Federal Communication Commission (FCC) regulates the use of unlicensed frequency bands and sets rules for operation of devices utilizing the unlicensed frequency bands for an indoor and an outdoor use.
The Unlicensed National Information Infrastructure (UNII) frequency band is part of the unlicensed frequency bands.
According to the FCC regulations, a range of channels of 5150-5250 MegaHertz (MHz) of the UNII (UNII1) are only available for an indoor use.